Turn curve into a path?
In blender, I know of no difference between curves and paths.
I believe that a few things could be happening.

1) Make sure that the orbs are children of the curve

2) See that Data > Path Animation is checked

3) You might also want the Frames value under Data > Path Animation to be equal to the length of your animation.

If all of these are done, and it is still not working, please upload your .blend file.